Thread-chasing mechanism



May a, 1923.

A. R. MITCHELL THREAD CHASING MECHANISM Filed Dec. 7, 1921 fzwerzfor Patented May 8, 1923.

ARTHUR R. MITCHELL, OF BBIDGEPORT, OHIO.

THREAD-CHASING MECHANISM.

Application filed December 7, 1921. Serial No. 520,538.

To all whom it may concern:

Be it known that I, ARTHUR R. MITCHELL, a citizen of the United States of America, and resident of Bridgeport, county of Belmont, and State of Ohio, have invented certain new and useful Improvements 1n Thread-Chasing Mechanisms, of which the following is a specification.

This invention relates broadly to threadchasing devices, and more particularly to a device for cutting threads on the necks of collapsible tubes.

The primary object of the invention is to provide a simple apparatus whereby threads may be rapidly and accurately out upon the necks of collapsible tubes by means of a chasing tool, to the end that the threads shall be of uniformly accurate form as dis tinguished from those formed, as ordinarily, in the tube casting process.

In describing the invention in detail, reference is herein had to the accompanying drawings, in which Figure 1 is a top plan view of a fragmentary portion of a machine embodying my invention, showing the tool holder and slide" Figure 2 is a sectional elevation of the machine; a

Figure 3 is a section taken substantially on line 3-3, Fig. 2; andv Figure 4 is an enlargedsectional elevation of the lower end portion of the tool holder.

Referring to said drawings, 1 indicates the top or bed of a table or stand of the general character which prevails in ordinary commercial forms of trimmers employed for detaching the surplus metal or ragged ends of the necks of collapsible tubes. In applying my invention to such stand, a transverse slot 2 is provided in the bed 1, and opposed guide members 3 and 4 are mounted upon said bed at opposite sides of said slot, said members having formed in their opposing faces rabbets or channels in which are fitted the lateral edges of a platelike slide 5. Carried by or formed on said slide is a vertical sleeve 6. In the preferred embodiment herein shown said sleeve is constituted by vertically alined bosses 6 and '6", the former rising from the upper face and the latter depending from the under face of said slide. Fitted for vertical movement in said sleeve is a member 7 having a socket 8 in its upper end for the reception of the stem portion of a thread-cutting tool 9, said member thus constituting a holder for the tool,

The lower end of the tool holder projects below the lower end of the sleeve 6 and is permanently received within a channel 10 provided in the periphery of a cam 11. carried by a rotary shaft 12, said channel being so shaped that, in each revolution of the cam, a complete forward and return reciprocation of the slide 5 and, consequently, the tool 9 is induced. An anti-friction roller 13 may be carried by that portion of the tool holder which is received in said channel 10.

Carried by the tool holder 7 in a position in which its oppositely disposed arms ride upon the periphery of the cam 11 at opposite sides of the channel 10 is'a crosshead 14; and interposed between said crosshead and the under face of the slide 5 is a spiral compression spring 15 which exerts a yielding tension for normally maintaining said tool holder depressed in a position inwhich the cutting tool 9 is lowered out of engagement with the neck of a properly positioned collapsible tube 16. The tubes to be acted upon are mounted upon a horizontally disposed mandrel 17 which is arranged to be rotated by any appropriate means.

The cam 11 has one portion 11 of its circumferential surface struck on a radius of such length that the tool holder is permitted to'be depressed to the extent that the tool carried thereby is withdrawn from operative relation to the neck of the mandrel-carried tube. Another surface portion 11 of said cam is struck on a radius of such greater length that when it is mounted by the crosshead 14 the tool holder is elevated against the tension of the spring 15 to a point in which the chasing tool 9 will chase threads of proper depth in the neck of the rotating tube 16.

Suitable means, as a set screw 19, is pro vided whereby the chasing tool may be securely held in adjusted position in the tool holder.

The cam-groove or channel 10 is accurately formed to actuate the slide 5 to travel the requisite distance for effecting the chasing of the neck of the tube. Instantly following the chasing operation, the crosshead rides from the cam surface 11 to the surface 11*. permitting the tool 9 to be withdrawn from engagement with the tube, and

this withdrawn position is maintained until the beginning of the next advance movement of the slide 5, when said cam surface 11 is again mounted by the crosshead.

The crosshead is preferably made separate from the tool holder and attached to the lower end of the latter by means of a screw 18, as indicated in dotted lines in Fig. 4.

\V hat is claimed is- 1. In a device for threading the necks of collapsible tubes, the combination with a rotary mandrel for carrying a tube, of a supporting stand, guide members carried by said stand, a slide arranged for travel on said guide members, a tool holder having vertical movement through said slide, a rotatable cam having a peripheral groove in which the lower end of said holder is received and by w iich the latter and said slide are reciprocated in a direction parallel to the axis of said mandrel, resilient means normally holding said tool holder depressed, and means coacting with said cam whereby said tool holder is maintained elevated against said resilient means during a portion of the reciprocating movement.

2. In a device for threading the necks of collapsible tubes, the combination with a rotary mandrel for carrying atube, of a supporting stand, guide members carried by said stand, a slide arranged for reciprocation on said guide members parallel to the axis of said mandrel, a tool holder carried by and vertically movable through said slide, a cutting tool mounted in the upper end of said holder,v means normally holding said tool holder depressed under yielding tension, a cam associated with the lower end of said tool holder and adapted in a portion of each revolution thereof to effect elevation of said tool holder with respect to said mandrel and also to actuate travel of said holder and said slide.

3. The combination with a rotary mandrel for carrying a collapsible tube, of mechanism for threading the necks of such tubes, said mechanism comprising a tool holder movable longitudinally at a right angle to the axis of the mandrel, a chasing tool carried by said tool holder, a reciprocable member by which said tool holder is carried, resilient means tending to maintain said holder in Withdrawn position, and a cam disposed in direct engagement with said holder and arranged both to advance said holder for presenting the tool to the work and to act through said holder for reciprocating the holder carrying member.

4t. The combination with a rotary mandrel for carrying a collapsible tube, of mechanism for threading the necks of such tubes, said mechanism comprising a tool holder movable longitudinally at a right angle to the axis of the mandrel, a chasing tool carried by said tool holder, a reciprocable memher by which said tool holder is carried, a cam having therein a peripheral groove in which the lower end of said tool holder is received and adapted to actuate reciprocation of said holder and its carrying member parallel to the axis of said mandrel, a spring normally holding said holder depressed, and a crosshead carried by said tool holder and riding upon the periphery of said cam, said cam being adapted, through said crosshead, to efiect elevation of said holder during a part of each revolution thereof.

in testimony whereof, I afiix my signature in presence of two subscribing witnesses.

ARTHUR H. MITCHELL. Witnesses CHARLES P. So LIoK, H. E. DUNLAP. 

